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Updated: May 5, 2026
Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
General active space commutator-based coupled cluster theory of general excitation rank for electronically excited
Mickaël Hubert1, Jeppe Olsen, Jessica Loras
1Laboratoire de Chimie et Physique Quantiques, IRSAMC, Université Paul Sabatier Toulouse III, 118 Route de Narbonne, F-31062 Toulouse, France.
Abstract:
We present a new implementation of general excitation rank coupled cluster theory for electronically excited states based on the single-reference multi-reference formalism. The method may include active-space selected and/or general higher excitations by means of the general active space concept. It may employ molecular integrals over the four-component Lévy-Leblond Hamiltonian or the relativistic spin-orbit-free four-component Hamiltonian of Dyall. In an initial application to ground- and excited states of the scandium monohydride molecule we report spectroscopic constants using basis sets of up to quadruple-zeta quality and up to full iterative triple excitations in the cluster operators. Effects due to spin-orbit interaction are evaluated using two-component multi-reference configuration interaction for assessing the accuracy of the coupled cluster results.
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